Miles's Taste Tests for 12AX7


I got four new 12AX7 tubes from Lord Valve for comparison purposes. I also had some barely used Chinese tubes, and some older tubes as well. I compared them in two small amps from the 60s.


New tubes

Old tubes


I used two amps, a Kalamazoo Model One and a Silvertone 1263. The Kalamazoo uses a single 12AX7 preamp tube and a 6BQ5 (EL84) output tube, has one channel with volume and tone controls, and a single, 10" speaker. I also tried it through the 4 ohm 2-12 Scorpion pair of a Peavey Heritage VTX combo.

The Silvertone came with three 7025's, two for preamps and one for tremolo, and has two 6V6's (slightly used RCA black glass) for output. It has two channels, with volume and tone on each channel, and a wimpy tremolo. I ran it through the 4 ohm 2-12 Scorpion pair of a Peavey Heritage VTX combo.

Both amps use tube rectifiers, multistage capacitor/resistor power supply filters, and point to point wiring.

The primary guitar was a Hagstrom 1 with two DiMarzio SDS-1s and completely flexible pickup selection. I also tried a BC Rich ST Platinum with a humbucker in the bridge slot.


No, these aren't the most popular amps. But there are plenty of tests that tell you what works in Fenders and Marshalls, already. These are representative of lower end amps you might find at garage sales, pawn shops, eBay, or in your parents' attic.

Tubes can make quite a difference, but so can everything else. In particular, the output transformer and speaker are at least as important as which tube you use. The differences between tubes in the Kalamazoo were not as apparent as in the Silvertone until I hooked the Kalamazoo to the Scorpion speakers.

Finally, these were more snacks than meals, first impressions only. I played with each tube for maybe five minutes.


There wasn't a real clear winner, although there was a clear loser.

The Snacks


If you can find the GE 7025 or R.T.N. 12AX7A (whatever that is) in NOS, you are probably set. Of current production tubes, I give the Sovtek 12AX7LPS a slight advantage with humbuckers, with the Ruby 12AX7A-C Selected second, but about even for single coil pickups. The EI ECC83 and GE JAN 12AX7WA were slightly behind both, but are still nice tubes. The unbranded generic Chinese tubes are fairly useless for a classic rock sound, but would work well for low volume clean sound (jazz, maybe) if you don't need any low end. I would only use the Realistic 12AX7/ECC83 in something like a tremolo oscillator - and then only if I were desperate.

I'd use any of the four newer tubes in the Kalamazoo, but in reality the original R.T.N. 12AX7A is still doing a fine job. I'm happy with the three newer tubes in the Silvertone, set up like this: Ruby 12AX7A-C Selected in the trem channel, Sovtek 12AX7LPS on the second channel (1 triode for each input), and the EI ECC83 in the mixer/inverter socket. I've more or less settled on the Sovtek 12AX7LPS for my Kalamazoo Model Two.

Other Notes

The Ruby appeared to be identical in construction to the cheap Chinese tubes. My guess is that Ruby simply takes the best of the lot and rebrands them (this has been confirmed by multiple sources -Miles). This would imply horrible quality control - but given the Chinese approach to mass manufacturing (volume over everything), this would not be a surprise.

The generic Chinese tubes were all pulled from new amplifiers that didn't sound right to their owners. Apparently some of the manufacturers aren't worrying about putting good tubes in their amps these days.

These results were first posted in the alt.guitar.amps newsgroup.

Last updated: 24 July 2000
Taste Test copyrighted 1999 by Miles O'Neal, Austin, TX. Incidentals copyright 1999 Miles O'Neal, Austin, TX. All rights reserved.
Miles O'Neal <> [remove the "XYZZY." to make things work!] c/o RNN / 1705 Oak Forest Dr / Round Rock, TX / 78681-1514